About us.....

Abingdon Carbon Cutters is a Community Action Group formed to help reduce the carbon footprint of Abingdon in response to climate change, and to promote a sustainable and resilient lifestyle for our town as fossil fuel stocks decline. We meet on the third Wednesday of each month at St Ethelwold's House, which is here.

At some meetings, we have guest speakers to present various topics, and at others we discuss our own personal actions to address climate change. The group has a focus on encouragement, both of one another, and of the town community.

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Sunday, May 24, 2009


Last night Pete and I went to an event at Science Live Oxford, an evening discussing biofuels with Ben Mayo (who works in the local biofuel industry).

Ben’s presentation centred around using biofuels for bin lorries, which have a surprisingly (until you think about it) high carbon footprint. The loads they carry, and the stop-start nature of the routes, means that they are very fuel hungry vehicles, and they can account for 15% of a local authority’s carbon footprint. They’re also difficult to run on alternative fuels – hybrids would need too many batteries and an LPG conversion compromises the load space to a large degree.

But the fact that they return to the depot after each route makes them ideal candidates for conversion to biodiesel – they can refuel at the depot rather than requiring a biodiesel distribution system.

Local authorities have been given ambitious carbon reduction targets by the government, and reducing the carbon footprint of their waste collections could be a very big step in the right direction. But what are the downsides?

Biodiesel is essentially plant oils treated chemically to make them less viscose (thick) (or you can use a twin tank system, which starts an engine using mineral diesel and then uses waste energy heat to heat the biodiesel until it’s runny enough to go through the engine properly).

Virgin vegetable oils (VO) are expensive – and controversial, since it is essentially converting a food product into a fuel. There’s also wider environmental impacts to consider. But they’re readily available, high quality and can be converted into a reliable, consistent and high quality biodiesel.

Waste vegetable oils (WVO), from the catering industry, have a superior environmental profile and are cheaper. But the fragmented sources and the varying product quality make it harder to produce consistent and high quality fuel. The problem here is that although older diesel engines aren’t fussy about their fuel, modern high-tech engines are. And commercial vehicles have tighter emissions controls than the domestic fleet.

Biodiesel has a different emissions profile than mineral diesel, and emits more nitrous oxides (NOx, which causes problems with local air quality but is also a greenhouse gas), but new technology allows NOx to be removed from exhaust gases.

If the technical problems can be overcome (and they can) then converting bin lorries to run on biodiesel made from waste oil is cheaper and more environmentally friendly – so it looks like a simple decision. Biodiesel gives effectively the same mpg as mineral diesel, and if made from waste oils have an 85-90% reduction in CO2 over the lifecycle of the fuel.

However, even if we convert all of our waste vegetable oil into biodiesel, we’re still only looking at a few percent of our total diesel requirements here in the UK. Biodiesel isn’t going to solve all of our problems, but what it does do is start to break away from the mentality that fossil fuels are the only answer. Other alternative fuels (fuel crops that grow on otherwise non-productive land, algae and seaweed, and renewable energy in general) can then benefit from a more positive environment and increased investment and research.

After Ben's presentation there was a group activity, looking at the various stakeholders who would be involved in a decision to convert bin lorries to run on biodiesel – the environmental officers, fleet managers, vehicle managers, the public, local catering outlets, environmentalists, etc.

One of the main concerns is that using biodiesel voids the manufacturers warranty on the vehicle, especially if fuel cannot be manufactured to the European standard (which is tricky, from WVO). Ben's solution to this is to define a reachable standard and then find a third-party insurer to take on the warranty – which makes the conversion a no-risk choice for the local council.

However, there are only two vehicle manufacturers in this sector (Mercedes and Dennis Eagle), and so a large fleet manager would have considerable sway over them. And as waste collections are generally outsourced (to companies like Biffa and Grundon), if they could be brought on board then the process could be made considerably easier.

Here in Oxfordshire, biodiesel is available to the general public via Golden Fuels (http://www.goldenfuels.com), a well-established co-operative that collects waste oil for processing into biodiesel that is then sold to consumers and local businesses.

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